Prime Minister Narendra Modi and Russian President Vladimir Putin on Friday signed the crucial $5 billion S-400 air missile defence system deal at the 19th India-Russia annual bilateral summit.
China was the first buyer of the S-400 and it is known to be the most advanced long-range air defence systems. An undisclosed number of the S-400 air missiles are already being delivered to China.
With this deal, there are chances that India will be imposed with US sanctions. Under Countering America's Adversaries through Sanctions Act or CAATSA, the US is allowed to impose sanctions on any country that has "significant transactions" with Iran, North Korea or Russia.
India is also considering to buy 4 Krivak-class frigates from Russia of which two of which will be built in India.
The summit began at Hyderabad House on Friday morning.
The Russian president, who leaves on Friday evening, is accompanied by a high-level delegation, including Deputy Prime Minister Yuri Borisov, Foreign Minister Sergey Lavrov and Trade and Industry Minister Denis Manturov.
(With inputs from PTI)